From 1992 to 2017, Autobus La Québécoise operated CIT Sorel-Varennes (CITVR) local and express service between Sorel-Tracy and Longueuil (link).

In 2017, Le Groupe Transbus won the contract to operate the CIT Sorel-Varennes (CITVR) / Exo Sorel-Vareenes routes (link).

In 2021, MRC de Pierre-de-Saurel decided to improve its transit services in a more local and regional vision, to centralize them into STACR and to rename them STC.

Since 2022, Sorel-Tracy local transit and express routes to Longueuil are now operated by Autobus Fleur de Lys. (link)

Exo Sorel-Varennes contract (Rt. 700, 707 and 709) is now served by Transdev Quebec (link) and Groupe Transbus operates some remaining Exo services in St. Amable and Varennes. (link)

Société des transports collectifs de Pierre-de-Saurel (STC)

Service de transport adapté et collectif régional (STACR) - Now replaced by STC